Process for enrichment of water gas



NOV. 16, 1954 A, WELTY, JR" ETAL 2,694,623

PROCESS FOR ENRICHMENT OF WATER GAS 7 Filed May 14, 1949 2 sfieets-sheet 1 12 Co+H CH CO.

COAL 01 Come TANZD IrzoN ORE METHANE 5 sYNTHEsls 4 (b --CL2 T WATER GAS GENERATOR,

summer .3 w'eeisek CYZbert a. Uu u gmmbors United States Patent 2,694,623 PROCESS FOR ENRICHMENT OF WATER GAS Albert B. wart in, Mountainside, and summi- B; Sweetser, Cranford, N; J., assignors to Standard Oil Development Company, a corporation of Delaware Application Ma 14, 1949, Serial No. 93,208 17 claims. (ems-197 The present invention relates to improvements .inthe art of converting coal or coke to a city gas containing forlmed methane and, therefore, of improved heating va ue.

Prior to this inventionit was lrnownthat carbonaceous material such as coal, when subjected to the influence of steam at high temperatures, was adapted ,to generate volatile constituents suitable for use as a fuel and which contained not onlyhydrogenand carbon monoxide but also methane, the methane being present ingreater quanmy in the fuel than that corresponding simply to the methane produced by destructive distillation of the coal. In other words, at least aportion of the carbon monoxide and hydrogen reacted to form methane, This process has been practiced abroad commercially and is generally referred to as the Lurgi process.

The present invention constitutes an improvement over the older process in several particulars including the employment of the fluidized solids technique, the us'eof at least two vessels, and the use of a cata lyst to promote the hydrogenation of the oxides of carbon to form methane. H"

The main object of the. present inVention theref re, is to produce a fuel gas of improved heating value in a process which is rnore economical, m'ereflexible, and in particular, whichresults in the formation of a fuel gas of increased heating value due to the presence of increased quantities of methane.

Another object of the present invention is to carry out continuously, a treatment of coal or cokein a two,- zone process so that the generation of hydrogen and carbon monoxideis carried'out ina zonephysicallysep arated from a second zone inwhieh methane synthesis occurs. Another object of thepresent invention is to preheat the fresh charge' of carbonaceous material in the methane synthesis zone thus obviating the necessity of preheating coal or coke outside of the said reaction zones,

Other and further objects of the invention will appear in the following more detailed description and claims.

Before proceeding with a detailed description of the process and the preferred embodiment thereof, it should be pointed out that heretofore it has beendemonstrated that water gas can be generated from coal or coke by contacting it with steamwhile the said coal or coke is in the form of a fluidized mass. The gas thus produced, however, has a relatively low B. t. u. value, generally of the order of about ZaOO B. t. u. per cubic foot, Sinchgas is suitable as a hydrocarbon synthesis feed gas, but is of too low quality for use as a city gas since the latter requires a higher 8'. t. 11; value.

It has previously been found that the heating value of the water gas thus produced can be increased by contacting the hot gas as it issues from the water gas generating zone with incoming coal or coke in a second zone, whereby methane is synthesized by contact of the carbon monoxide and hydrogen in the water gas with the coal or coke. In such an operation the incoming coal or coke feed contacts the water gas in an initial syn- 2,694,623 feeesfisrr. 1 1

thesis, zone in which the coalcrcokeis formed into a fluidized mass. The solid carbonaceousjeed fromthe initial zone then gravitates into a ,secondaryZQne where itis again procured in fluidized form andwherein the water gas is formedby contact of the, carbonaceous material with steam at a temperature of about .1800 F. or any known suitable temperature.- .In order to support the exothermic reaction ocenfling in this latter zone, comm'ercially pure oxygen is also, fed intoflthesaidlatter zone causing combustion of a portion of the carbonaceous material and the release of heat Ash of relatively low carbon content iswithdrawn fromalower portion. of the Water gas generation zone and this mayberejected-from the system, or the sensible heat thereof may be utilized in any known manner. H I

It has now been found that increased yields. of methane can be obtained in the product gas ,byincluding in the coal or coke fed to the carbonization and methane synthesis zone, relatively smallamountsof a catalyst adapted to promote the methane synthesis. The yields of methane obtained by passing a mixture of carbon monoxide and hydrogen into contactwith a coke formed by low temperature carboniz ation (8 0 0 to..1,0.00-, F.) with and without the inclusion of ,an,iron.catalyst have been determined by experiment and the results appearv hereinafter. At this point it is simply stated that .the,.con: centration of methane in the product gaswhen a, catalyst was presentwas increased over andabove. that where no catalyst was used It also was determined, that when a catalyst is ,employedas indicated, the methane v.synthesis proceeds, at a lower temperature than when a catalyst is not employed. r I

It is an iinportant feature of this invention to employ cheap catalysts, such as iron ores. Another adyantage of the present invention is that one am se an iron hydrocarbon synthesis catalyst which has been reje t d from a hydrocarbon, synthesis process due to permanent loss of activity since at thehigher temperatures prevailing in the methane synthesis zone of the present process, this catalyst will possess sluflicient activity. 0

In the accompanying drawing there is shown, diagrarn matically, in Fig. l anappara'tu's' layout in which a preferred embodiment of the inventionmay be carried into effect, and in Fig. 2 a modification thereof." 7, p l

Referring in detail to Fig. 1, numeral l rcfers to a carbonizing (if coal is pr'e'sent) and methane synthesis one and 2 represents a water gas generation zone In perating the process', coal or coke and iron ore, which may be at ordinary atmospheric'temperature', is charged from hopper 3 through an aerated line 4 intoz'one 1, the coal or coke and ore having been previously ground to a particle size ranging within the approximate limits" of 40 to 400 microns.

It should be stated at this point that the system about to be described is operated under s'up'e'ratinosph'eric pressure and some suitable means, such as lock hoppersoperating in parallel must be employed in feeding the coal or coke. Thus, hopper 3 may receive the coal or coke charge at atmospheric pressure, undergo pressurization to system pressure ,(or slightly higher) and thereafter its content of coal or.coke may be discharged via 4 into carbonizer 1. As indicated, the feed may be continuous by employing two hoppers such as 3, to operate in parallel. Instead of lock or pressurized hoppers, the coal or coke may be brought up to system pressure by means of a plurality of aerated standpipcs operating in series.

As stated, the carbonaceous material is formed into a fluidized mass in zone 1 in the usual manner bycontrolling the superficial velocity of upflowing gas, which as will subsequently more, fully appear, passes from low-. er vessel 2 to vessel 1. The said gas yelocitiescausing the fiuidization of the carbonaceous material are within the range of from /2 to 5 feet per second. As usual, the reactor is provided with a gas distributing means G, such as a screen or grid. in order to provide for good distribution of the gas entering the zone. Then depending on the superficial gas velocities, (superficial velocity signifies the calculated velocity at the vessel inlet. assuming no solids in said vessel) and the amount of carbonaceous material in the said Zone, the bed will have an u per dense phase level at L and above L there will be a dilute hase suspension of solids in gas. Although not actually shown in the drawing. it will be understood by those who are familiar with this technique that it is customary to dispose one or more solids separating devices (e. g. centrifugal separators) in the upper portion of the vessel in order to separate from the issuin gases. entrained solids. whi h are returned to the fluidized bed by suitable pipes. The product gas eventually issues from reactor 1 through line and CO2 removed therefrom as by scrubbing with an aqueous alkali solution.

Carbonized solids are wi hdrawn continuously from zone 1 through an aerated line 5 controlled by valve 6 and char ed to zone 2. the water gas generation zone. As previously indicated. both steam. which enters the generator thr u h line 7. and oxygen which enters throu h line 8. are charged into the said generator bel w a distribution me ns G2 and then proceed upwardly at he su erficial vel city rates disclosed ab ve in connecti n with the description of the operation of zone 1. u this zone the steam reacts with the carb naceous solids to form water gas, or a mixture of hydro en and carbon monoxide. Meanwhile, the oxygen reacts with can bonaceous material to form oxides of carbon with simnltaneous release of heat. This aseous mixture proceeds f m. he fl i ed m ss upw rdly throu h e it. nine 9 and then is dischar ed into zone 1 Where it under es reaction as nreviouslv indicated. As in the case. of vessel 1, the solids in vessel 2 are pr cured in the fluidized state by controlling the superficial velocity of the unfio inrz gasif rm material and the re ult will be as in ve sel 1. the forming of a dense fluidized mass f solids in gas which. de ending on the amount of solids actu lly resent. will have an upper dense phase level at L2 above which will he a dilute ph se. No attem t is made to senarate solids from the dilute phase and they are ermitted to pass with the ga iform material from vessel 2 into vessel 1. Ash resulting from the treatment in vessel 2 is withdrawn thr u h line 10 and ma be rejected from the system. However, it is preferable to recycle to vessel 1 a rtion of this ash since it contains iron catalyst. To this end. therefore, the ash is withdrawn via lines 10 and branch line 11, charged in a current of asiform material such as steam in line 12 and convevod pneumatically to a separator 13 where it is separated from the steam or other gas, and thence conveyed via line 14 to hopper 3.

In Fi 2 there is shown a modification of the ap a ratus illustrated in Fig. l, the main difference being that in order to su ly heat to the water gas generation zone, solids are withdrawn from the synthesis zone and the water gas zone, and burned in the presence of air in a separate combustion zone and thereafter transferred to the water gas generation zone. This, of course, eliminates the necessity for employing pure oxygen.

Referring in greater detail to Fig. 2, represents the water gas generation zone and 21 the methane synthesis and coking zone. In both zones, as in the case of the apparatus depicted in Fig. 1, the solids are maintained in the form of dense fluidized beds having upper dense phase levels at La and L4, respectively. As before, coal or coke and iron ore is withdrawn from hopper 23 via line 24 and discharged into the methane synthesis zone where, under the influence of heat, the coal (if that is the material) is converted to coke, and simultaneously, carbon monoxide and hydrogen obtained from water gas generator 20 are at least, in part, converted to methane in the presence of the iron ore also present in the methane synthesis zone. The carbonaceous solids are withdrawn from zones 20 and 21, via lines 26 and 38, respectively, controlled by valves 27 and 39, respectively, and charged into an air stream introduced into the system through line 30 to form therein a suspension which is conducted into a transfer line combustion zone 31 Where combustion occurs and, of course, the temperature of the solids is increased.

A transfer line combuster is simply an elongated conduit through which a dilute suspension flows at a rather rapid rate and its function is to cause burning of carbonaceous material to CO2 predominately, so as to obtain the maximum amount of heat. The fumes are withdrawn from the combuster before there is an opportunity for the CO2 to be reduced to CO to any substantial degree, and hence, the time element as well as small excess of air are important features of this tech- 111 ue.

bf course, circulation rates between the burner and the water gas set are sufficiently high to support the endothermic reaction therein occurring. The amount of hot solids fed to the water gas generating zone will depend on the degree of steam conversion and the carbonaceous solids residence time. Simple manipulative steps will serve to maintain proper heat supply and temperature conditions so that steam conversions as high as 80% or higher are achieved. Thus, about 75-80 lbs. of hot solids per lb. of steam converted at a solids temperature of about 200 F. higher than that prevailing in the water gas zone, should be delivered to the said water gas zone. These figures apply to a commercial installation and the amounts given are sufficient to support the reaction, for preheat and to offset radiation losses.

The suspension is withdrawn from the combustion zone 31, through line 32 and thence charged into a solids-gas separating device 33 which may be, for example, one or more centrifugal separators wherein the solids are separated from the combustion fumes, thence conveyed via line 35, controlled by valve 36 into a line 37 containing steam to form a suspension of the hot solids in the said steam, which suspension is then conveyed via line 41 into the bottom of water gas generator 20. As previously explained, in connection with the description of Fig. l, the Water gas reaction occurs in 20 and the products pass via line 29 into 21 where at least a portion of the oxides of carbon and hydrogen react to form methane. The product is finally withdrawn from 21, via line 25 and delivered to purification and storage (not shown).

As usual, vessels 20 and 21, respectively, are provided with foraminous members G3 and G4, respectively, disposed in the vessels for the purpose of effecting good distribution of the gasiform material passing therethrough and into the fluidized beds. And as usual, transfer lines, such as 26 and 35 operating on the standpipe principle, are provided with spaced gas taps (not shown) through which fiuidizing gas may be introduced for the purpose of effecting smooth flow of the solids in the said standpipes. Attention is directed to the fact that heat exchange cooling coil 42 is shown disposed in the bed of fluidized solids in vessel 21. This provides means for preventing the temperatures therein from reaching too high a value, for the data hereinafter set forth has revealed that the reaction promoting the formation of methane is best performed within a relatively restricted temperature range. This cooling means, although not shown in vessel 1 of Fig. l, is now disclosed as being desirable in most instances.

Another modification in the invention involves employing a fluidized bed of solids in the combustion vessel in lieu of the transfer line combustion zone 31 shown in Fig. 2. However, it is preferred to use the transfer line combuster since this procedure affords a greater degree of conversion of carbon to carbon dioxide which, of course, means that, as stated, from a given weight of carbonaceous material, a maximum quantity of heat is released. In other words, if a fluidized bed of solids was subjected to combustion in the form of a fluidized bed similar to that shown, say, in vessel 1 of Fig. l, the combustion would result in the formation of less carbon dioxide and more carbon monoxide, in most instances, than would be the case were a transfer line combuster employed.

Product is recovered overhead through line 25 and before delivering to storage, it is usually treated to remove COz. Ash withdrawn from vessel 20, Fig. 2, through line 40, is in part recycled to vessel 21.

As heretofore pointed out, several test runs were made in order to determine the efficiency of the present process and the results of these runs are set forth below in tabular form. In the runs carried out, the coke employed was a commercially available coke produced by low temperature carbonization, that IS, carbomzrng of bituminous coal at a temperature of the order of 900 F.

Enrichment of water gas with methane [250p s. i. g. pressure, 45% C0 55% HzinFeed-(Flxed Bed Unlt).]

Table I Table II; Table III Coke 2.2% Coke-+22% Catalyst Coke Magnetite Hematite Run 84A 79A 85A 103 102 99 7.8 4. 0 20.2 7.2 2 37. 6 44. 0 22. 2 37. S 36. 8 39. 9 43. 0 30.0 42. 2 36. 8 14. 7 9.0 26.7 12. 8 16. 2 C2 7 0. 7 Lower heating 7 value 1 B. t. u./C. F.:

Scrubbed for G02 removal 324 395 356 509 381 09 Containing C O: 321 364 341 406 354 367 The foregoingdata clearlyshow that the inclusion of synthesis. Consequently, we prefer to operate at rela' an; iron ore in: relatively small amounts results in the-production in theproduct gas of increasedquantitiesof' The data (and themethane at the lower temperatures. same would be true of fluid operation) show that magnetite is a superior catalyst to hematite'but they further show that at 1200 F. hematite results in the'production of over four times the quantity of methane in the product as does coke not containing the said hematite. It is evident that the optimumv temperature-for maximum methane formationusing magnetite as .the catalyst is lower than .for maximum formation-with coke alone.

It is evident from the above tabulation that an appreciable increase in the calorific value of the gas can be attained by the removal of carbon dioxide. Consequently, it is preferred-to scrub the gas with. a solvent such as water or ethanolamine for carbon dioxide. removal. Since thegas is generated under pressure, scrubbing can also be conducted under pressure and water-is an effective solvent for carbon dioxideunderthese conditions. for the process, additional enrichment ofthe-water gas is'obtained .by carbonization of the coal with production of coal gas.

It has been observed that the following conditionsof operation have been found to. give'best results; Hence, there is set forth below a'tabulation of the preferred range of operating. conditions in both the methane synthesis zone and the water gas generation-zone. be observed, as previously pointed out, thatrthe system works under superatmospheric pressure. It will alsobe observed that in the methanesynthesis-zonel for best results which, of course, means maximumproductionof methane, the temperature range 18 relatively: restricted andcrltioal.

When coal isused in place-of coke as the feed It is to Particle Size of Solids Carbon Concentration 40400 mu. 5l5%.

With respect to the catalystadded with the coal or coke, we prefer to use a cheap material such asan iron ore, for example, magnetite, hematite or siderite. No promoter, such as the alkali metal carbonates used in conventional hydrocarbon synthesis catalysts, is required when operating according to the conditionsof the present process. Also no reduction of the catalyst is. required'prior to its use in the process. While no catalyst is required in the water gas generating, zone, the presence of the iron oxide in thecarbonaceous material fed to this zone has no deleterious effect on the water gas reaction.

It has been found that high concentrations of steam in'the water gas havean adverse effect onthje methane tively high steam conversion in the water gas generator, for example, above about Numerous modifications of the present invention not specifically mentioned herein will occur to those who are familiar with this art without departing from the spirit thereof.

What isaclaimedis: 1. A-continuousprocessfor producing a fuel gas of improved heating value which comprises 1 charging cold,

. powdered carbonaceous material and finely divided oxiclic ironkor'e catalytic material to an initial methane synthesis zone, maintaining said carbonaceous solids and oxidic iron ore catalytic material in the form of a'fluidized mass having a lower, densephase suspension and an interface separating an upper, dilute phase suspension, contacting the dense fluidized suspension of carbonaceous material and oxidie iron ore catalytic material with gasiforrn material containing hydrogen and carbon monoxide at temperatures of about 1100"1300 F. and at pressures .of

-. about l00-to 6.00lb's. per sq. inch for a periodsufiicient tionzone attemperatures,ofiabout HOW-.2000 F. andat pressures of about-l00+600 lbs-per sq. inch for a periodsufiicient toconverta substantial-part of said;carb.onaceous solids and; gasiform' reaction material into gasiformmaterial containingcarbonmonoxideand hydrogen, chargiug; the latter gasiform material directly to the first-named, methane synthcsis zoueas the aforesaid gasi- I forrn.contactingmaterial and-recovering from said firstnamed zone a gaseous fuel containing-carbon monoxide, hydrogen and methane.

2. The method set forth in cla m 1 in which heatnecest sary to support theendothermicreact-iontaking place in the water gas generation zone is supplied by.charging-hot solids to .said zone.

3. The method set forth in claim l'in whichsolid residue is withdrawn from the water gas generatingv zone and recycledto the methane synthesis zone.

4. The methodset forth inclaim l in which the carbonaceous material is withdrawn from the methane synthesis ,zone, partially burned in-the presence of air in a separate combustion zone to increase itstemperature to at least water gas generating temperatures and thereafter charging the thus heated carbonaceous material to the water gas generation zone.

5, The method set forth in. claim 1 in which a cooling fluid is circulated in indirect heatexchange relationship with the material undergoing: conversion in the methane synthesis zone.

6. A continuous process for producing a fuel gas of improved heating value which comprises charging cold powdered carbonaceous material and finely divided oxidic iron ore catalytic material to an initial methane synthesis zone, maintaining said carbonaceous solids and oxidic iron ore catalytic material in the form of a fluidized mass having a dense, lower phase suspension and an interface separating a dilute phase suspension, contacting the dense fluidized suspension of carbonaceous material and oxidic iorn ore catalytic material with a gas containing hydrogen and carbon monoxide at temperatures of about 1100-1300 F. and at pressures of about 100 to 600 lbs. per sq. inch for a period suflicient to convert a substantial amount of hydrogen and carbon monoxide to normally gaseous hydrocarbons, including methane, withdrawing a mixture of hot solids comprising carbonaceous and oxidic iron ore catalytic material from the methane synthesis zone and charging said mixture to a water gas generation zone, maintaining the mitxure of solids in the water gas generation zone in the form of a fluidized mass having a dense lower phase suspension and an interface separating a dilute phase suspension, charging steam and oxygen through said dense phase suspension in said water gas generation zone, maintaining said water gas generation zone at pressures of about 100600 lbs. per sq. inch and at temperatures of about 1500-2000 F by the combustion of a portion of the carbonaceous material with the oxygen, maintaining contact between the steam and said dense phase suspension in said water gas generation zone for a period of time sufficient to convert a substantial part of said carbonaceous solids and steam into gasiform material containing carbon monoxide and hydrogen, charging the latter gasiform material directly to the firstnamed, methane synthesis zone as the aforesaid gasiform contacting material and recovering from said first-named zone a gaseous fuel containing carbon monoxide, hydrogen and methane.

7. A continuous method for producing a fuel gas of improved heating value which comprises charging powdered coke and finely divided oxidic iron ore catalytic material to an initial methane synthesis zone, maintaining the said coke and oxidic iron ore catalytic material in the form of a fluidized bed having a lower dense phase suspension and an interface separating an upper dilute phase suspension in said initial zone, contacting the dense phase suspension with a gas containing hydrogen and carbon monoxide at temperatures of about 1l00-l300 F. and at pressures of about 100600 lbs. per sq. inch for a sufficient period of time to effect at least partial conversion of said hydrogen and carbon monoxide to normally gaseous hydrocarbons including methane, withdrawing a mixture of hot solids comprising coke and oxidic iron ore catalytic material from said methane synthesis zone and charging said mixture to a water gas generating zone, maintaining the mixture of solids in said water gas generation zone in the form of a fluidized bed having a lower, dense phase suspension and an interface separating an upper, dilute phase suspension, charging gasiform material including steam through said dense phase suspension in said water gas generation zone, maintaining said last-named zone at temperatures of about 1500-2000 F. and at pressures of about 100-600 lbs. per sq. inch, maintaining contact between said gasiform material and said dense phase suspension for a sufficient period of time to effect the conversion of substantial quantities of said coke and gasiform material into gasiform product containing carbon monoxide and hydrogen, charging the latter gasiform product directly to said methane synthesis zone as the aforesaid gasiform contacting material, and recovering from said methane synthesis zone a fuel containing carbon monoxide, hydrogen and methane.

8. The method of claim 7 in which the iron oxide is in the form of magnetite.

9. The method set forth in claim 7 in which solid residue is withdrawn from the water gas generating zone and recycled to the methane synthesis zone.

10. The method set forth in claim 7 in which the carbonaceous material is withdrawn from the methane synthesis zone, partially burned in the presence of air in a separate combustion zone to increase its temperature to at least water gas generating temperatures and thereafter charging the thus heated carbonaceous material to the water gas generation zone.

11. The method set forth in claim 7 in which a cooling fluid is circulated in indirect heat exchange relationship 8 with the material undergoing conversionin the methane synthesis zone.

12. The continuous method of producing a fuel gas of improved heating value which comprises charging powdered coal and finely divided oxidic iron ore catalytic material to an initial methane synthesis zone, maintaining the said powdered coal and oxidic iron ore catalytic material in the form of a fluidized bed having a lower, dense phase suspension and an interface separating an upper dilute phase suspension in said zone, contacting the dense phase suspension with a gas containing hydrogen and carbon monoxide at temperatures of about 11001300 F. and at pressures of about l00600 lbs. per sq. inch for a suflicient period of time to carbonize said coal and to effect at least partial conversion of the hydrogen and carbon monoxide to methane, withdrawing a mixture of hot solids comprising carbonized coal and oxidic iron ore catalytic material from said methane synthesis zone, charging said mixture of solids to a water gas generation zone, maintaining the mixture of solids in said water gas generation zone in the form of a fluidized bed having a lower, dense phase suspension and an interface separating an upper, dilute phase suspension, charging a gasiform material including steam through said dense phase suspension in said water gas generation zone, maintaining said last-named zone at temperatures of about 15002000 F. and at pressures of about -600 lbs. per sq. inch, maintaining contact between said gasiform material and said dense phase suspension in said water gas generation zone for a sufiicient period of time to effect the conversion of substantial quantities of said gasiform material and said carbonized coal into gasiform product containing carbon monoxide and hydrogen, charging the latter gasiform product directly to said methane synthesis Zone as the aforesaid gasiform contacting material, and recovering from said methane synthesis zone a fuel containing carbon monoxide, hydrogen and methane.

13. The method set forth in claim 12 in which the iron oxide is in the form of magnetite.

14. The method set forth in claim 12 in which solid residue is withdrawn from the water gas generating zone and recycled to the methane synthesis zone.

15. The method set forth in claim 12 in which the carbonaceous material is withdrawn from the methane synthesis zone, partially burned in the presence of air in a separate combustion zone to increase its temperature to at least water gas generating temperatures and thereafter charging the thus heated carbonaceous material to the water gas generation zone.

16. The method set forth in claim 12 in which a cooling fluid is circulated in indirect heat exchange relationship with the material undergoing conversion in the methane synthesis zone.

17. A continuous method of producing a fuel gas of improved heating value which comprises charging powdered coke and finely divided oxidic iron ore catalytic material to an initial methane synthesis zone, maintaining the said coke and said oxidic iron ore catalytic material in the form of a fluidized bed having a lower, dense phase suspension and an interface separating an upper, dilute phase suspension in said initial zone, contacting the dense phase suspension with a gas containing hydrogen and carbon monoxide at temperatures of about 11001300 F. and at pressures of 100-600 lbs. per sq. inch for a sufiicient period of time to effect at least partial con- 1 version of said hydrogen and carbon monoxide to normally gaseous hydrocarbons including methane, withdrawing a mixture of hot solids comprising coke and oxidic iron ore catalytic material from said methane synthesis zone and charging said mixture to a water gas generation zone, maintaing the mixture of solids in said water gas generation zone in the form of a fluidized bed having a lower, dense phase suspension and an interface separating an upper, dilute phase suspension, charging gasiform material including steam and oxygen through said dense phase suspension in said water gas generation zone, maintaining said last-named zone at pressures of about l00600 lbs. per sq. inch and at temperatures of about l5002000 F. by the combustion of a portion of the coke with the oxygen, maintaining contact between the steam and the dense phase suspension in said water gas generation zone at said temperatures and pressures for a sulficient period of time to effect conversion of substantial quantities of said coke and steam to gasiform product containing carbon monoxide and hydrogen, charging the latter gasiform product directly to said methane synthesis zone as the aforesaid gasiform contacting material, and recovering from said methane synthesis zone a fuel containing carbon monoxide, hydrogen and methane.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 956,734 Sabatier May 3, 1910 1,898,967 Schneider et a1. Feb. 21, 1933 1,955,025 Sabel et al Apr. 17, 1934 10 Number Name Date 2,094,946 Hubmann Oct. 5, 1937 2,458,862 Krebs Apr. 3, 1948 FOREIGN PATENTS Number Country Date 296,443 Great Britain Oct. 24, 1929 503,158 Great Britain Apr. 3, 1939 OTHER REFERENCES Kalbach, Chemical Engineering, Jan. 1947, pages 105108. 

1. A CONTINUOUS PROCESS FOR PRODUCING A FUEL GAS OF IMPROVED HEATING VALUE WHICH COMPRISES CHARGING COLD. POWDERED CARBONACEOUS MATERIAL AND FINELY DIVEDED OXIDIC IRON ORE CATALYTIC MATERIAL TO AN INITIAL METHANE SYNTHESIS ZONE, MAINTAING SAID CARBONACEOUS SOLIDS AND OXIDIC IRON ORE CATALYTIC MATERIAL IN THE FORM OF A FLUIDIZED MASS HAVING A LOWER, DENSE PHASE SUSPENSION AND AN INTERFACE SEPARATING AN UPPER, DILUTE PHASE SUSPENSION, CONTACTING THE DENSE FLUIDIZED SUSPENSION OF CARBONACEOUS MATERIAL AND OXIDIC IRON ORE CATALYTIC MATERIAL WITH GASIFORM MATERIAL CONTAINING HYDROGEN AND CARBON MONOXIDE AT TEMPERATURES OF ABOUT 1100*-1300* F. AND AT PRESSURES OF ABOUT 100 TO 600 LBS, PER SQ. INCH FOR A PERIOD SUFFICIENT TO CONVERT A SUBSTANTIAL AMOUNT OF HYDROGEN AND CARBON MONOXIDE TO NORMALLY GASEOUS HYDROCARBONS INCLUDING METHANE, WITHDRAWING A MIXTURE OF HOT SOLIDS COMPRISING CARBONACEOUS MATERIAL AND OXIDIC IRON ORE CATALYTIC MATERIAL FROM THE METHANE SYNTHESIS ZONE AND CHARGING SAID MIXTURE TO A WATER GAS GENERATION ZONE MAINTAINING THE MIXTURE OF SOLIDS IN SAID WATER GAS GENERATION ZONE, IN THE FORM OF A FLUIDIZED MASS HAVING A LOWER, DENSE PHASE SUSPENSION AND AN INTERFACE SEPARATING AN UPPER, DILUTE PHASE SUSPENSION, CHARGING GASIFORM MATERIAL IN SAID WATER STEAM THROUGH SAID DENSE PHASE SUSPENSION IN SAID WATER GAS GENERATION ZONE, MAINTAINING SAID WATER GAS GENERATION ZONE AT TEMPERATURES OF ABOUT 1500*-2000* F. AND AT PRESSURES OF ABOUT 100-600 LBS, PER SQ. INCH FOR A PERIOD SUFFICIENT TO CONVERT A SUBSTANTIAL PART OF SAID CARBONA- 